Chemical Bonding: Ionic, Covalent and Metallic Bonds

Why Atoms Bond

Atoms bond to achieve a stable electron arrangement, usually a full outer (valence) shell of 8 electrons (the octet rule), by losing, gaining or sharing electrons.

Ionic Bonding

Forms between a metal and a non-metal. The metal loses electrons to become a positive ion (cation) and the non-metal gains electrons to become a negative ion (anion). The oppositely charged ions attract strongly. Example: Sodium chloride (NaCl) - Na loses 1 electron, Cl gains 1 electron.

Covalent Bonding

Forms between two non-metals that share pairs of electrons. Example: Water (H2O), where oxygen shares electrons with two hydrogen atoms. Covalent bonds can be single, double or triple depending on how many electron pairs are shared.

Metallic Bonding

Occurs between metal atoms, where electrons are delocalised and free to move in a "sea of electrons" around positive metal ions. This explains why metals conduct electricity and are malleable.

Comparing Properties

Ionic compounds have high melting points and conduct electricity when dissolved or molten. Covalent compounds often have lower melting points and generally do not conduct electricity.